U.S. patent number 6,651,445 [Application Number 10/192,112] was granted by the patent office on 2003-11-25 for food chiller with ductless air circulation.
This patent grant is currently assigned to Delta T, LLC. Invention is credited to Joshua A. Broehl, Chris W. Cicenas, George A. Clark.
United States Patent |
6,651,445 |
Clark , et al. |
November 25, 2003 |
Food chiller with ductless air circulation
Abstract
A food chiller includes a container into which cool air is moved
over the cold sink of a Peltier effect thermoelectric device and
directly into the container. Return air from the container exits
the bottom of the container directly into the fan for
recirculation. Elimination of a long air duct system simplifies the
construction and reduces heat loss.
Inventors: |
Clark; George A. (Lewis Center,
OH), Cicenas; Chris W. (Columbus, OH), Broehl; Joshua
A. (Worthington, OH) |
Assignee: |
Delta T, LLC (Racine,
WI)
|
Family
ID: |
29584031 |
Appl.
No.: |
10/192,112 |
Filed: |
July 10, 2002 |
Current U.S.
Class: |
62/3.6; 62/3.62;
62/457.6 |
Current CPC
Class: |
F25B
21/04 (20130101); F25D 17/06 (20130101); F25B
2321/021 (20130101); F25B 2321/0251 (20130101); F25D
2317/0651 (20130101); F25D 2317/0661 (20130101); F25D
2317/0683 (20130101) |
Current International
Class: |
F25D
17/06 (20060101); F25B 21/04 (20060101); F25B
21/02 (20060101); F25B 021/02 () |
Field of
Search: |
;62/3.2,3.6,3.62,457.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
US 6,381,965, 5/2002, Ghoshal (withdrawn).
|
Primary Examiner: Tapolcai; William E.
Attorney, Agent or Firm: Andrus, Sceales, Starke &
Sawall
Claims
We claim:
1. A food chiller comprising: a supporting base including a
housing; a Peltier effect thermoelectric device disposed in the
housing between a cold sink and a hot sink; an enclosed food
container positioned adjacent the housing and separated therefrom
by a base baffle plate; said container having an outer wall
extending from the base baffle plate; said base baffle plate
supporting the thermoelectric device and separating the cold sink
and the hot sink; a separate baffle overlying at least a portion of
the cold sink and spaced from said base baffle plate, said baffle
having a generally planar food-supporting upper surface and a
peripheral outer edge spaced from the container outer wall to
define a generally annular air flow opening directly from the cold
sink to the interior of the container, and said baffle having a
central air flow opening from the container interior to the cold
sink; and, a fan disposed adjacent said baffle directly beneath
said central opening and in fluid communication with the cold sink
to generate a circulating air flow over said cold sink and directly
into the container through said annular opening.
2. The apparatus as set forth in claim 1 wherein said cold sink
comprises a generally flat base with integral spaced fins extending
generally perpendicular to the base.
3. The apparatus as set forth in claim 2 wherein said cold sink is
made of aluminum.
4. The apparatus as set forth in claim 2 wherein said base baffle
plate supports the cold sink flat base and said baffle comprises an
integral portion of said cold sink.
5. The apparatus as set forth in claim 4 wherein said cold sink is
made of aluminum.
6. The apparatus as set forth in claim 1 comprising a conduit
connecting the container interior to ambient outside air.
7. The apparatus as set forth in claim 6 including a valve in said
conduit to control the flow of ambient outside air.
8. The apparatus as set forth in claim 1 comprising an exhaust vent
from the interior of the container.
9. The apparatus as set forth in claim 8 wherein said vent
comprises an adjustable slot in the container or the cover.
10. The apparatus as set forth in claim 1 including control means
for said thermoelectric device for controlling the air flow
temperature.
11. The apparatus as set forth in claim 10 wherein said control
means comprises means for reversing the polarity of the current
supplied to the thermoelectric device.
12. The apparatus as set forth in claim 10 wherein said control
means comprises means for controlling the magnitude of current and
voltage supplied to the thermoelectric device.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a device for chilling fresh fruit
and other fresh food products and, more particularly, to an
improved countertop fruit chiller utilizing a Peltier effect
thermoelectric device.
Thermoelectric devices operating in accordance with the well know
Peltier effect have been used as cooling/heating devices for many
years. Such a thermoelectric device comprises an array of
semiconductor couples connected electrically in series and
thermally in parallel. The semiconductor couples are sandwiched
between metalized ceramic substrates. When DC electric current is
applied in series to the thermoelectric device, it acts as a heat
pump with heat being absorbed on the cold side, thereby cooling it,
while heat is dissipated at the other side. Reversing the current
causes the direction of heat flow to be reversed. Attaching a heat
sink and a cold sink to the respective hot and cold sides may
enhance the efficiency of the thermoelectric device.
Peltier effect devices have long been used to provide coolers
and/or heaters for keeping foods fresh or for warming foods for
serving. It has also been found and is well known to use forced-air
convection to aid in heat transfer. A small electric fan is
typically used to circulate air past the cold sink and into and
through a container for the food, while another fan moves ambient
outside air across the heat sink to dissipate heat from it.
Although chillers for fresh fruit and other perishable food
products are well known in the art, the market success of such
devices has been limited. There appear to be a number of reasons
for this lack of market success. One is the cost and heat transfer
efficiency of the solid state thermoelectric modules. In addition,
the need to provide circulation of cool air to attain the greatest
cooling efficiency has led to complex duct systems which add
substantially to the cost of the containers, typically made of
molded plastic materials. Long and complex air circulation duct
systems also result in heat loss and pressure drop, both of which
decrease the efficiency or add to the product cost.
SUMMARY OF THE INVENTION
In accordance with the present invention, a chiller for fresh fruit
or other perishable food products utilizes a construction, which
minimizes manufacturing cost while still allowing optimized cooling
airflow and permits the use of a relatively smaller thermoelectric
module.
Thermoelectric modules of increased efficiency, such as disclosed
in U.S. Pat. No. 5,448,109, are particularly suitable for use in
the fruit chiller of the subject invention.
In its broadest aspect, the food chiller of the present invention
comprises a base housing for mounting a Peltier effect
thermoelectric module sandwiched between a cold sink and an
opposite heat sink. A cool air circulation fan circulates air
through the food container and over the cold sink. To reduce
manufacturing cost there is no separate duct system. As the air
exits the circulation fan it impinges the cold sink and directly
enters the food container.
A food container portion is adjacent the base housing and contains
an enclosing sidewall and a removable or openable cover for
retrieval of the food.
In a preferred overall embodiment the housing containing the
thermoelectric device is integrated with the food-containing
portion thus minimizing the number of components to manufacture and
therefore the manufacturing cost.
The food container portion is normally closed with a removable or
openable cover such that cooling air is continuously recirculated.
In one embodiment, however, an outside ambient air supply conduit
communicates with the cooling duct system and includes a metering
device to admit a controlled flow of outside air to assist in
purging the cooling duct system of ethylene gas and other ripening
by-products of fruit. The metering device may comprise a small
diameter tube connected to the duct system upstream of the fan.
To help maintain the interior temperature of the container, a
removable insulating sleeve may be inserted into the container. The
sleeve is shaped to conform to the interior of the enclosing
sidewall. The removable cover may also be provided with an
insulating liner.
Various arrangements of partitions may be placed within the
container to divide the container into different temperature zones
by varying the flow of cooling air through the zones. Such
partitions may be vertically disposed to extend upwardly from the
container bottom wall or may be horizontally disposed and attached,
for example, to a central tower or to the container sidewall.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing the general arrangement of the
fruit chiller of the subject invention.
FIG. 2 is a vertical section through the fruit chiller shown in
FIG. 1.
FIG. 3 is a perspective view of the fruit chiller of FIG. 1 cut in
half for viewing of the interior components.
FIG. 4 is a view similar to FIG. 3 with the upper baffle
removed.
FIG. 5 is a top perspective view of the fruit chiller of FIG. 1
with the cover removed.
FIG. 6 is a view similar to FIG. 5 with the upper baffle
removed.
FIG. 7 is a detailed portion of the vertical section view of FIG.
2.
FIG. 8 is a perspective view of an alternate embodiment of the
fruit chiller cut vertically in half for viewing of the interior
components.
FIG. 9 is a view similar to FIG. 8 with the upper cold sink plate
removed.
FIG. 10 is a top perspective view of the alternate embodiment of
the fruit chiller of FIG. 8 with the cover removed.
FIG. 11 is a view similar to FIG. 10 with the upper cold sink plate
removed.
FIG. 12 is a detailed vertical section through the alternate
embodiment of the fruit chiller of FIG. 8.
FIG. 13 is a perspective view of an alternate embodiment of the
fruit chiller cut vertically in half for viewing of the interior
components.
FIG. 14 is a vertical section through the alternate embodiment of
the fruit chiller of FIG. 13.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIGS. 1 and 2, there is shown a fruit chiller 14 in accordance
with one embodiment of the present invention. The fruit chiller
includes a supporting base 1 for supporting the chiller on a
horizontal surface. There is space inside the base for housing
various components of the cooling system, which will be described
in detail herein. A container 2 is seated on base 1. A removable
cover 3 provides access to the food to be preserved. The base 1,
container 2 and removable cover 3 may all be made of injection
molded plastic materials. The base 1 is preferably opaque and the
container 2 and cover 3 transparent.
Referring also to FIGS. 3-7, the base 1 is suitably supported on
legs 15 to provide an open space beneath the base for the entry of
ambient cooling air. The lower interior of base 1 defines a
substantially open ambient air chamber 16 defined generally by base
side walls 17 and a base baffle plate 13.
The container 2 and the food products contained therein are cooled
with thermoelectric module 12 utilizing the well-known Peltier
effect. The thermoelectric module 12 is mounted in the base baffle
plate 13 and positioned generally horizontally in the plane of
baffle plate 13. By applying a DC current to the module, heat will
be absorbed at one face (in this case the upper side of 12),
thereby cooling it. Heat will be dissipated at the other face of
the module (in this case the lower side of 12), thereby heating it.
As is also well known in the prior art, a cold sink 10 is attached
to the upper face of the module 12 and a heat sink 11 is attached
to the lower face of the module. The cold sink 10 is typically made
of aluminum and includes a flat base 18 and a series of closely
spaced fins 19. The cold sink is best viewed in FIG. 6. Similarly,
the heat sink 11 includes an aluminum base plate 20 and integral
closely spaced fins 21. The heat rejected by the operating
thermoelectric module 12 at the heat sink 11 is dissipated by a
flow of ambient air through the ambient air chamber 16.
A centrifugal fan 9 draws air in through holes 5 in an upper baffle
6 overlying the cold sink 10, and discharges the air radially past
the cold sink fins 19 into (optional) space 8 between the base
plate 18 of the cold sink and the upper baffle 6. The air enters
the food container interior 24 as it passes between upper baffle 6
and cold sink base 18 and through an annular opening 4. In this
manner the air within container interior 24 is recirculated and
cooled.
The embodiment described above minimizes manufacturing cost by
reducing the number of components to be manufactured.
In another embodiment shown in FIGS. 8 through 12 the cold sink 27
is made of up of a base plate 26 preferably made of aluminum and an
upper plate 23 also preferably made of aluminum. Bosses 25 separate
base plate 26 and upper plate 23. Air enters the centrifugal fan 9
through holes 22 in upper cold sink plate 23 and exits fan 9 in a
radial manner between the cold sink plates 26 and 23. Air enters
the food container 24 via opening 4 after it is chilled by coming
contact with cold plates 26 and 23. This embodiment reduces
manufacturing cost by reducing the number of components to be
manufactured. This embodiment also provides a low-profile cooling
system thus maximizing the interior room for food storage.
Ripening fruit is known to emit ethylene gas and other by-products
of organic decomposition. It may be desirable to exhaust these
gasses by regular or periodic replacement of the cooling air
recirculating within the container interior 24. Referring
particularly to FIGS. 13 and 14, an ambient air conduit 29
comprising a small diameter metering tube extends from the side
wall of the food container 2 to the holes 5 where a small volume
flow of ambient outside air is drawn in by the cold sink fan 9 and
mixed with the recirculated cooling air. As shown, the ambient air
conduit 29 opens above the holes 5 just upstream of the inlet to
the fan 9. It is believed, however, that the conduit could connect
to the duct system at another location therein. The inflow of
ambient air may be regulated with the use of an optional pinch
valve or a metering valve 30 at the inlet end of the conduit 29. To
provide for the corresponding exhaust of ethylene and other gaseous
by-products, it is preferred to provide a small leak between the
container 2 and the cover 3, however, a manually adjustable vent
slot may also be used. Such a slot could be located in either the
wall of the container 2 or in the cover 3.
As indicated previously, the thermoelectric module 12 is normally
configured so the upper face is cold while the lower face is hot.
Because reversal of the polarity of the supplied current to the
thermoelectric module causes the direction of heat flow to be
reversed, the fruit chillers of either of the embodiments described
herein may also be utilized to warm the fruit to promote or enhance
ripening. In this alternate configuration the upper face of the
thermoelectric module 12 is hot while the lower face is cold.
Certain fruits may often be purchased in a green or semi-ripe
condition. One example is bananas which are often purchased in some
semi-ripe condition and allowed to ripen in the open air. By
reversal of the supplied current to the thermoelectric module 12, a
green or semi-ripe fruit may be ripened more quickly by warming
and, when ripe, preserved for a longer time by again reversing the
current to provide a cooling air supply to the container 24.
In general, temperature control is an excellent, and by far the
best means, of controlling ripening in fruit. As discussed above,
warming may be used to enhance and promote ripening of green or
semi-ripe fruit, but after the fruit has ripened, cooling is the
best means available to slow the biological ripening processes and
preserve the fruit for a longer period of time.
The direction of heat transfer of the thermoelectric module 12 can
be reversed as mentioned above. The level of heating and cooling
can also be controlled by control of the level of supplied current
and voltage. In this manner, the user may, for example, select a
set point to ripen fruits at a desirable rate or, conversely, a
cooling set point to maintain ripened fruit at a temperature found
to make the fruit most palatable. Other cooling or warming
strategies may also be utilized, either with manual settings by the
user or by using programmed microprocessor control.
* * * * *